For years a concern in the care of dogs used in laboratories has been cage space and allowance for exercise. These issues and concern for social interaction with conspecifics and humans were heightened with passage of PL99-198 in 1985 which required that minimum standards for exercise be established for dogs. The long-term objectives proposed in this application are to determine confinement conditions that will allow for the well-being of laboratory dogs, i.e., to provide satisfactory care of research dogs within reasonable and practical laboratory conditions. First it will be necessary to operationally define and to develop reliable quantitative means of assessing well-being. Measures of physical well-being are comparatively easy to establish. However, meaningful and practical indices of psychological well-being are more difficult to measure but are imperative. The specific aims of these studies are to determine whether dogs housed in cages without additional opportunity for exercise and interaction with other dogs differ physiologically or behaviorally from similarly housed dogs-allowed exercise with or without conspecifics. In Experiment 1, dogs housed individually in conventional cages will be assigned to one of three conditions, nonexercise (group NE), exercise individually (group EI), or exercise with a conspecific (group EC). Dogs in group EI will be released individually into an empty room and allowed opportunity for exercise for 20-minute periods three times a week. Dogs in group EC will be released and allowed opportunity for exercise in a similar manner but with a conspecific rather than individually. Dogs in group NE will not have additional opportunity for exercise or social interaction. At regular intervals, blood samples will be analyzed for determination of plasma cortisol levels and immune parameters and behavioral patterns will be recorded and analyzed.